1. Field of the Invention
The present invention relates to a driving apparatus, shutter apparatus and camera which moves a driven member having a moving load from an initial position of charging to a position of completion of charging against the load.
2. Description of Related Art
A conventional charge mechanism which moves a driven member having a moving load from an initial position of charging to a position of completion of charging against the moving load is constructed in such a way that a lever member 401 rotates about one rotation axis as shown in FIG. 23.
With reference to FIG. 23 which is a perspective view showing an entire conventional charge mechanism, the conventional charge mechanism will be explained in detail.
Reference numeral 401 denotes a lever member which is supported in a manner rotatable about an axial portion 402a laid on a first base plate 402 as the rotation axis, pressed in the thrust direction of the axial portion 402a by a dropout prevention member (not shown) with a tiny gap. Reference numeral 401a denotes an input side arm portion of the lever member 401, 401b denotes an input pin laid in an integrated fashion on the input side arm portion 401a and 401c denotes an output side arm portion of the lever member 401.
Reference numeral 403 denotes a driven member, which is supported in a manner rotatable about an axial portion 402b laid on the first base plate 402 as the rotation axis, pressed in the thrust direction of the axial portion 402b by a dropout prevention member (not shown) with a tiny gap. At one end of the driven member 403, the axial portion 403a is laid in an integrated fashion and a roller 404 is attached in a manner rotatable about the axial portion 403a as the rotation axis. The dropout prevention member (not shown) acts on the roller 404 in the same way.
Reference numeral 405 denotes a power spring (torsion spring) located on the driven member 403 in such a way as to be coaxial with the axial portion 402b and its one end contacts a spring stopper 402c laid on the first base plate 402 and its other end contacts a spring stopper 403b of the driven member 403 and gives the driven member 403 clockwise torque about the axial portion 402b as the rotation axis.
Reference numeral 406 denotes a charge input lever and is supported in a manner rotatable about an axial portion 407a as the rotation axis, laid on a second base plate 407 which is placed orthogonal to the first base plate 402 and pressed in the thrust direction of the axial portion 407a by a dropout prevention member (not shown) with a tiny gap. Reference numeral 406a denotes an input side arm portion of the charge input lever 406 and receives a force Fch which rotates the charge input lever 406 counterclockwise about the axial portion 407a as the rotation axis to charge this charge mechanism.
Reference numeral 406b denotes an output side arm portion of the charge input lever 406. 406c denotes an output pin laid in an integrated fashion on the output side arm portion 406b, which contacts the input pin 401b of the lever member 401 and transmits power to the lever member 401. Reference numeral 408 denotes a return spring, one end of which is supported by a spring stopper portion 407b laid on the second base plate 407 and the other end of which is hooked on to a hole 406d of the charge input lever 406. Hereby the return spring 408 gives the charge input lever 406 clockwise torque about the axial portion 407a as the rotation axis.
Reference numeral 407c denotes a stopper provided on the second base plate 407 which contacts the side of the output side arm portion 406b of the charge input lever 406 and blocks the clockwise rotation of the charge input lever 406 by the return spring 408.
Then, the operation of the conventional charge mechanism in the above described configuration will be explained.
First, when a force Fch is applied to the input side arm portion 406a of the charge input lever 406, the charge input lever 406 rotates counterclockwise about the axial portion 407a as the rotation axis. In this way, the input pin 401b on the input side arm portion 401a is pressed by the output pin 406c on the output side arm portion 406 and the lever member 401 rotates clockwise about the axial portion 402a as the rotation axis. This causes the output side arm portion 401c of the lever member 401 to press the roller 404 against the force of the power spring 405 and rotate the driven member 403 counterclockwise about the axial portion 402b as the rotation axis.
Then, charging is finished when the driven member 403 has rotated by a predetermined angle.
Then, the operation of the conventional charge mechanism will be explained in detail with the state of a charging load in operation taken into consideration. The power spring 405 is a torsion spring but it will be expressed as a tensile coil spring in the figures used in the following explanations as required.
FIG. 24 is a plane view of charge mechanism (charge input lever 406 placed on the second base plate 407, etc., is omitted) indicating the lever member 401 and the driven member 403 placed on the first base plate 402 when charging is started, and both the rotation angle of the lever member 401 (driving member) and the rotation angle of the driven member 403 are 0xc2x0.
In the same figure, components have dimensions as indicated in the figure and suppose the rotation moment that the power spring 405 gives to the driven member 403 is kxcex81 when charging is started. Here, k denotes a spring constant of the power spring 405 per unit rotation angle when the driven member 403 rotates. Furthermore, xcex81 denotes a displacement angle from a free state of the driven member 403.
F in the figure denotes a force that the input pin 401b of the lever member 401 receives from the output pin 406c of the charge input lever 406 to balance with kxcex81, P10 denotes the force that the roller 404 receives from the output side arm portion 401c of the lever member 401, which is equal to a reaction force by the force of the power spring 405 that the output side arm portion 401c of the lever member 401 receives through the roller 404.
From a balance relationship between forces, the following expressions are obtained. Here, for simplicity of explanation, frictions of various portions are ignored.
(Fxc2x7cos 29.16xc2x0)xc3x973.90=P10xc3x975.79xe2x80x83xe2x80x83(1.1)
(P10xc2x7cos 54.35xc2x0)xc3x9710.00=kxcex81xe2x80x83xe2x80x83(1.2)
From expressions (1.1) and (1.2), F=0.292kxcex81 is obtained.
Here, suppose k=1[gf/deg](=980[dyn/deg]), xcex81=10xc2x0. Then, F=2.92[gf](=2860[dyn]) is obtained.
FIG. 25 is a plane view of charge mechanism in a first half charging state after charging has further advanced from the state in FIG. 24. The rotation angle of the lever member (driving member) 401 is 14xc2x0 and the rotation angle of the driven member is 10xc2x0 after charging is started.
In the same figure, components have dimensions as shown in the figure and the rotation moment that the power spring 405 gives to the driven member 403 is k(xcex81+10xc2x0). Reference character F denotes a force that the input pin 401b of the lever member 401 receives from the output pin 406c of the charge input lever 406 to balance with k(xcex81+10xc2x0), P20 denotes a force that the roller 404 receives from the output side arm portion 401c of the lever member 401, which is equal to the reaction force by the force of the power spring 405 that the output side arm portion 401c of the lever member 401 receives through the roller 404.
The following expressions are obtained from the relationship of balance between forces. Here, for simplicity of explanation, frictions of various components are ignored.
(Fxc2x7cos 15.16xc2x0)xc3x973.90=P20xc3x974.98xe2x80x83xe2x80x83(1.3)
(P20xc2x7cos 30.35xc2x0)xc3x9710.00=k(xcex81+10xc2x0)xe2x80x83xe2x80x83(1.4)
From Expressions (1.3) and (1.4), F=0.153k(xcex81+10xc2x0) is obtained.
Here, suppose k=1[gf/deg](=980[dyn/deg]), xcex81=10xc2x0. Then, F=3.07[gf](=3000[dyn]) is obtained.
FIG. 26 is a plane view of charge mechanism in an intermediate charging state after charging has further advanced from the state in FIG. 25. The rotation angle of the lever member (driving member) 401 is 30.2xc2x0 and the rotation angle of the driven member 403 is 18.5xc2x0 after charging is started.
In the same figure, components have dimensions as shown in the figure. In the intermediate state of charging, the rotation moment that the power spring 405 gives to the driven member 403 is k(xcex81+18.5xc2x0). Reference character F denotes a force that the input pin 401b of the lever member 401 receives from the output pin 406c of the charge input lever 406 to balance with k(xcex81+18.5xc2x0), P30 denotes a force that the roller 404 receives from the output side arm portion 401c of the lever member 401, which is equal to the reaction force by the force of the power spring 405 that the output side arm portion 401c of the lever member 401 receives through the roller 404.
The following expressions are obtained from the relationship of balance between forces. Here, for simplicity of explanation, frictions of various components are ignored.
(Fxc2x7cos 1.04xc2x0)xc3x973.90=P30xc3x974.94xe2x80x83xe2x80x83(1.5)
(P30xc2x7cos 5.65xc2x0)xc3x9710.00k(xcex81+18.5xc2x0)xe2x80x83xe2x80x83(1.6)
From expressions (1.5) and (1.6), F=0.127k(xcex81+18.5xc2x0) is obtained.
Here, suppose k=1[gf/deg](=980[dyn/deg]) and xcex81=10xc2x0. Then, F=3.63[gf](=3560[dyn]) is obtained.
FIG. 27 is a plane view of charge mechanism in a second half charging state after charging has further advanced from the state in FIG. 26. The rotation angle of the lever member (driving member) 401 is 55.5xc2x0 and the rotation angle of the driven member is 33xc2x0 after charging is started.
In the same figure, components have dimensions as shown in the figure. In the second half charging state, the rotation moment that the power spring 405 gives to the driven member 403 is k(xcex81+33xc2x0). Reference character F denotes a force that the input pin 401b of the lever members 401 receives from the output pin 406c of the charge input lever 406 to balance with k(xcex81+33xc2x0), P40 denotes a force that the roller 404 receives from the output side arm portion 401c of the lever member 401, which is equal to the reaction force by the force of the power spring 405 that the output side arm portion 401c of the lever member 401 receives through the roller 404.
The following expressions are obtained from the relationship of balance between forces. Here, for simplicity of explanation, frictions of various components are ignored.
(Fxc2x7cos 26.34xc2x0)xc3x973.90=P40xc3x976.25xe2x80x83xe2x80x83(1.7)
(P40xc2x7cos 34.15xc2x0)xc3x9710.00=k(xcex81+33xc2x0)xe2x80x83xe2x80x83(1.8)
From expressions (1.7) and (1.8), F=0.216k(xcex81+33xc2x0) is obtained.
Here, suppose k=1[gf/deg](=980[dyn/deg]) and xcex81=10xc2x0. Then, F=9.29[gf](=9110[dyn]) is obtained.
FIG. 28 is a plane view of charge mechanism in a charging completion state after charging has further advanced from the state in FIG. 27. The rotation angle of the lever member (driving member) 401 is 66.5xc2x0 and the rotation angle of the driven member is 44xc2x0 after charging is started.
In the same figure, components have dimensions as shown in the figure. In the charging completion state, the rotation moment that the power spring 405 gives to the driven member 403 is k(xcex81+44xc2x0). Reference character F denotes a force that the input pin 401b of the lever member 401 receives from the output pin 406c of the charge input lever 406 to balance with k(xcex81+44xc2x0), P50 denotes a force that the roller 404 receives from the output side arm portion 401c of the lever member 401, which is equal to the reaction force by the force of the power spring 405 that the output side arm portion 401c of the lever member 401 receives through the roller 404.
The following expressions are obtained from the relationship of balance between forces. Here, for simplicity of explanation, frictions of various components are ignored.
(Fxc2x7cos 37.34xc2x0)xc3x973.90=P50xc3x977.90xe2x80x83xe2x80x83(1.9)
(P50xc2x7cos 56.15xc2x0)xc3x9710.00=k(xcex81+44xc2x0)xe2x80x83xe2x80x83(1.10)
From expressions (1.9) and (1.10), F=0.457k(xcex81+44xc2x0) is obtained.
Here, suppose k=1[gf/deg](=980[dyn/deg]) and xcex81=10xc2x0. Then, F=24.7[gf](=24200([dyn]) is obtained.
Based on the above described results, the graphs shown in FIGS. 7A and 7B give a summary of the relationship between the rotation angle of the driven member and input load of the lever member (which will be described later).
Here, suppose a shutter apparatus provided with the above described charge mechanism (e.g., see Japanese Patent Publication No. S62(1987)-17737 (pp2-5, FIG. 2) and Japanese Utility Model Application Laid-Open No. H4(1992)-17930 (pp2-3, FIG. 1)).
FIG. 30 to FIG. 36 show a conventional charge mechanism of a focal plane shutter (hereinafter simply referred to as a xe2x80x9cshutter apparatusxe2x80x9d) mounted on a single-lens reflex camera. The focal-plane shutter has a front curtain and a rear curtain. FIG. 30 is a perspective view indicating main components of the shutter apparatus, FIG. 31 is a plane view of the shutter apparatus showing a state after completion of running until charging is started, FIG. 32 is a plane view of the shutter apparatus in a first half charging state, FIG. 33 is a plane view of the shutter apparatus in an intermediate state of charging (switching of charge lever axes), FIG. 34 is a plane view of the shutter apparatus showing a second half charging state, FIG. 35 is a plane view of the shutter apparatus in a state immediately before completion of charging and FIG. 36 is a plane view of the shutter apparatus in a state of overcharge. In these FIGS. 31 to 36, suppose straight lines H5, H6 and H7 are common straight lines.
In FIGS. 30 to 36, reference numeral 501 denotes a charge lever (lever member) which is supported to an axial portion 502a laid on a shutter base plate 502 in a rotatable manner and pressed in the thrust direction of the axial portion 502a by a dropout prevention member (not shown) with a tiny gap. Reference numeral 501a denotes an input side arm portion of the charge lever 501, 501b denotes an input pin (input portion) laid in an integrated fashion on the input side arm portion 501a, 501c1 denotes a front curtain side output arm portion of the charge lever 501, 501c2 denotes a rear curtain side output arm portion of the charge lever 501.
Reference numeral 503 denotes a front curtain driving lever (driven member) which is supported to an axial portion 512a laid on the shutter base plate 502 in a rotatable manner and pressed in the thrust direction of the axial portion 512a by a dropout prevention member (not shown) with a tiny gap. At the end of the one arm portion 503c of the front curtain driving lever 503, an axial portion 503a is laid in an integrated fashion and a roller 504 is supported to the axial portion 503a in a rotatable manner. This shutter base plate 502 acts as a dropout prevention member of the roller 504.
At the end of the other arm portion 503d of the front curtain driving lever 503, a front curtain driving pin 503e is laid in an integrated fashion. On the front curtain driving lever (driven member) 503, a power spring (torsion spring) 505 is located in such a way as to be coaxial to the axial portion 512a. 
One end of the power spring 505 is supported to a shutter speed adjustment member (not shown) and the other end is hooked on to a spring stopper (not shown) of the front curtain driving lever 503. Hereby, the power spring 505 gives the front curtain driving lever 503 clockwise torque about the axial portion 512a as the rotation axis. A front curtain main arm 516 is supported to an axial portion 502g laid on the shutter base plate 502 in a rotatable manner. Furthermore, a front curtain sub-arm 517 is supported to an axial portion 502h laid on the shutter base plate 502 in a rotatable manner. Then, a slit formation blade (first blade) 518a of a blade group 518 making up the front curtain has a slit formation portion 518e. 
Of the blade group 518, a second blade 518b, a third blade 518c and a fourth blade 518d are supported to the front curtain main arm 516 and front curtain sub-arm 517 in a rotatable manner using a caulking dowel 519a, etc., and both arms 516, 517 and each blade together forms a parallel link (publicly known configuration). Furthermore, an armature holding portion 503f is formed above the arm portion 503d of the front curtain driving lever 503 to hold a magnet armature 523 by means of an armature axis 524 with a certain degree of freedom. Then, a yoke 525 wound with a coil 526 is fixed to a base plate (not shown), which attracts and holds the armature 523 when power is supplied to the coil 526, and releases the armature 523 when the power supply to the coil 526 is interrupted. Shutter timing is controlled using the above described operation.
Reference numeral 513 denotes a rear curtain driving lever (driven member), which is supported to an axial portion 512b laid on the shutter base plate 502 in a rotatable manner and pressed in the thrust direction of the axial portion 512b by a dropout prevention member (not shown) with a tiny gap. At one end of the arm portion 513c of the rear curtain driving lever 513, an axial portion 513a is laid in an integrated fashion and a roller 514 is supported to the axial portion 513a in a rotatable manner.
The shutter base plate 502 acts as a dropout prevention member for the roller 514. At one end of the arm portion 513d of the rear curtain driving lever 513, a rear curtain driving pin 513e is laid in an integrated fashion. On the rear curtain driving lever (driven member) 513, a power spring (torsion spring) 515 is located in such a way as to be coaxial with the axial portion 512b. One end of the power spring 515 is supported to a shutter speed adjustment member (not shown) and the other end is hooked on to a spring stopper (not shown) of the rear curtain driving lever 513. Hereby the power spring 513 gives the rear curtain driving lever 513 clockwise torque about the axial portion 512b as the rotation axis. The rear curtain main arm 520 is supported to an axial portion 502i laid on the shutter base plate 502 in a rotatable manner. Furthermore, a rear curtain sub-arm 521 is supported to an axial portion 502j laid on the shutter base plate 502 in a rotatable manner.
Furthermore, a blade group 522 making up the rear curtain is constructed of four blades as in the case of the front curtain. Reference numeral 522e in FIGS. 32 to 35 denotes a slit formation portion in the blade group 522. Each blade of the blade group 522 is supported to the rear curtain main arm 520 and the rear curtain sub-arm 521 in a rotatable manner using a caulking dowel 519b, etc., and both arms 520, 521 and each blade together forms a parallel link (publicly known configuration). Furthermore, an armature holding portion 513f is formed above the arm portion 513c of the rear curtain driving lever 513 and the armature holding portion 513f holds a magnet armature 527 by means of an armature axis 528 with a certain degree of freedom of movement.
A yoke 529 wounded with a coil 530 is fixed to a base plate (not shown), which attracts and holds the armature 527 when power is supplied to the coil 530, and releases the armature 527 when the power supply to the coil 530 is interrupted. Shutter timing is controlled using the above described operation. Reference numeral 502d denotes an aperture formed on the shutter base plate 502 through which a light passes and 502e denotes a long hole portion which is formed on the shutter base plate along a movement track of the front curtain driving pin 503e and 502f denotes a long hole portion which is formed on the shutter base plate along a movement track of the rear curtain driving pin 513e. Reference numerals 511a and 511b denote buffering members for receiving the front curtain driving pin 503e and rear curtain driving pin 513e when running of the front curtain is completed.
The charge mechanism of the conventional shutter apparatus as described above sets a maximum width from the input pin 501b laid in an integrated fashion on the input side arm portion 501a to the left end of the shutter apparatus to 12.6 mm (see FIG. 33) and sets the stroke of the input pin 501b (distance between straight line H5 and straight line H6) to 4.25 mm.
Furthermore, a charge input lever (not shown) which contacts the input pin 501b of the charge lever 501 to give the charge lever 501 torque in the same relationship as reference numeral 406 in FIG. 23 is provided.
The above described charge mechanism in which the lever member 401 simply rotates around one rotation axis involves inconvenience that when charging is started and when charging is completed, an angle formed between the straight line (L in FIGS. 24 to 29) connecting the central axis of the input pin 401b of the lever member 401 and the center of the axial portion 402a, and the line (H in FIGS. 24 to 29) orthogonal to the direction of the force F increases and the component force in the direction of the rotation axis 402a of the lever member 401 of the force that the input pin 401b receives from the output pin 406c of the charge input lever 406 is large (that is, axial loss is large), causing the force that rotates the lever member in the charge direction (clockwise direction) to be lost.
It is an object of the present invention to provide a small driving apparatus with a low charging load. The present invention is especially designed to reduce axial loss by reducing the component force in the axial direction during charging, reduce displacement at the input end in the direction orthogonal to the direction of the input load and thereby increase the driving efficiency.
One aspect of the driving apparatus of the present invention includes the following: A driving source, a driven member, an energizing member which energizes the driven member in a predetermined direction, a lever member rotatable by receiving the driving force from the driving source at an input portion, which contacts and charges the driven member, and a main body which includes a first engaging portion and a second engaging portion and supports the lever member. Here, the lever member includes a first engaged portion which engages with the first engaging portion and a second engaged portion which engages with the second engaging portion, and the lever member is rotated around a first axis by engaging the first engaging portion and the first engaged portion with each other, and in the middle of rotation, the lever member is rotated around a second axis by engaging the second engaging portion and the second engaged portion with each other.
One aspect of the shutter apparatus of the present invention includes the following: A driving source, a front curtain constructed of a plurality of blades, a rear curtain constructed of a plurality of blades, a first driving lever which drives charging of the front curtain, a second driving lever which drives charging of the rear curtain; and a driving force transmission member rotatable by receiving the driving force from the driving source, which includes a first arm portion which contacts the first driving lever and transmit the driving force and a second arm portion which contacts the second driving lever and transmits driving force. Here, the driving force transmission member starts charging when the distance between the rotation center and the point of contact with the first driving lever is greater than the distance between the rotation center and the point of contact with the second driving lever and is set through switching of the rotation center at some midpoint so that the distance between the rotation center and the point of contact with the second driving lever is greater than the distance between the rotation center and the point of contact with the first driving lever.
One aspect of the camera of the present invention includes the above described shutter apparatus.
Features of the driving apparatus, shutter apparatus and camera of the present invention will become more apparent from the following detailed description of preferred embodiments of the invention with reference to the drawings.